JRuby to Java invokedynamic dispatch

[Christian Thalinger]

On Jun 8, 2011, at 11:10 PM, Attila Szegedi wrote:
> Woo-hoo!

I agree :-)

> 
> On Jun 8, 2011, at 9:48 PM, Charles Oliver Nutter wrote:
> 
>> Hello friends! I have another update!
>> 
>> I've just landed preliminary work to make JRuby directly bind Ruby to
>> Java calls that were normally done via reflection! Currently only
>> no-arg methods that return primitives, CharSequence/String, or void
>> get patched straight through, but in those cases it makes a solid
>> performance difference.
>> 
>> Here's two benchmarks before direct binding and after:
>> 
>> BEFORE (using invokedynamic, but bound to a DynamicMethod wrapper
>> around java.lang.reflect.Method
>> 
>> Measure System.currentTimeMillis, long becoming Fixnum
>> 0.277000   0.000000   0.277000 (  0.278000)
>> 0.188000   0.000000   0.188000 (  0.188000)
>> 0.191000   0.000000   0.191000 (  0.191000)
>> 0.221000   0.000000   0.221000 (  0.221000)
>> 0.198000   0.000000   0.198000 (  0.199000)
>> Measure java.lang.Thread#name, String entering Ruby
>> 0.520000   0.000000   0.520000 (  0.520000)
>> 0.380000   0.000000   0.380000 (  0.380000)
>> 0.383000   0.000000   0.383000 (  0.383000)
>> 0.378000   0.000000   0.378000 (  0.378000)
>> 0.388000   0.000000   0.388000 (  0.389000)
>> 
>> AFTER (using invokedynamic and MHs all the way to the target)
>> 
>> Measure System.currentTimeMillis, int becoming Fixnum
>> 0.173000   0.000000   0.173000 (  0.172000)
>> 0.126000   0.000000   0.126000 (  0.126000)
>> 0.137000   0.000000   0.137000 (  0.137000)
>> 0.148000   0.000000   0.148000 (  0.148000)
>> 0.147000   0.000000   0.147000 (  0.147000)
>> Measure java.lang.Thread#name, String entering Ruby
>> 0.521000   0.000000   0.521000 (  0.521000)
>> 0.276000   0.000000   0.276000 (  0.276000)
>> 0.274000   0.000000   0.274000 (  0.274000)
>> 0.274000   0.000000   0.274000 (  0.274000)
>> 0.276000   0.000000   0.276000 (  0.276000)
>> 
>> In the latter case, this is only a tiny bit slower than a JRuby core
>> class method that constructs a Ruby String, so the dispatch overhead
>> of Ruby to Java has almost completely disappeared! Amazing!
>> 
>> This can be disabled with jruby.invokedynamic.java=false, but since
>> it's showing such a good perf improvement I've got it on by default
>> right now.
>> 
>> - Charlie
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> 
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